Control of Eye Movements—Pathology
In addition to the pathways described above, each ocular motor nucleus also receives input for saccadic and pursuit eye movements that do not involve the vestibular nuclei. These pathways ultimately…
Cochlear Receptors
The cochlea receives dual innervation: afferent fibers, which originate from cell bodies in the adjacent spiral ganglion efferent fibers, which originate in the brainstem. Both types of fibers form synapses…
Muscles of Facial Expression: Lateral View
FACIAL NERVE DISORDERS Facial weakness is caused by both central and peripheral lesions, and differentiating between the two frequently requires close examination. Peripheral facial weakness involves both the upper and…
Facial Palsy
OTHER ETIOLOGIES OF FACIAL NEUROPATHY Lyme disease is a relatively common infectious cause of an acute unilateral or bilateral facial neuropathy. Symptoms typically include systemic symptoms (e.g., arthralgia, fever, rash),…
Cytoarchitecture of Spinal Cord Gray Matter
Posterior Horn. Many neurons in the six laminae of the posterior horn receive direct synaptic input from spinal afferent fibers that enter the spinal cord via the posterior roots and…
Pathologic Causes of Vertigo
The eighth cranial nerve is vulnerable to fractures involving the petrous part of the temporal bone and by tumors affecting the brainstem or cerebellum. Vertigo may be caused by central…
Spinal Origin or Termination of Major Descending Tracts and Ascending Pathways
The descending pathways shown in parts A, B, C, and D have a variety of actions on spinal circuitry, including the modulation of somatosensory input and the production of motor…
Facial (VII) Nerve
THE MOTOR DIVISION Fibers arise from the motor facial nucleus, located in the reticular formation of the lowest part of the pons. The nucleus is posterior to the superior olive,…
